ENDOUROLOGY

Ureteroscopic treatment of lower pole calculi: comparison of lithotripsy in situ and after displacement
Schuster TG, Hollenbeck BK, Faerber GJ, Wolf JS Jr.
From the Department of Urology, University of Michigan, Ann Arbor, Michigan
J Urol 2002; 168:43-5

• Purpose: Ureteroscopic management is a viable option for lower pole calculi less than 2 cm. Recently a technique was described to displace the calculus into a more accessible calix using a nitinol basket or grasper before lithotripsy. We compared the efficacy and safety of this technique with in situ treatment of small and intermediate lower pole calculi.
• Materials and Methods: We retrospectively reviewed the records of 95 ureteroscopy cases performed at our institution from January 1997 through August 2001 for renal calculi located only in the lower pole. Preoperative patient characteristics, stone size, operative details, complications and outcomes were compared for calculi treated in situ and those displaced before treatment.
• Results: Adequate followup was available on 78 patients. Patients in the displacement group were statistically older, more often had a preoperative indwelling ureteral stent and had a mean operative time that was 16 minutes longer (p=0.04). Average stone diameter in the in situ and displacement groups was 8 and 10.3mm., respectively (p=0.04). In patients with radiographic followup greater than 1 month complete success was obtained for 77% of stones 1 cm. or less treated in situ versus 89% treated with displacement first (p=0.43). For calculi greater than 1 cm. complete success was obtained for 2 of the 7 (29%) treated in situ versus all 7 (100%) treated with displacement (p=0.005).
• Conclusions: When treating lower pole calculi 1 to 2 cm. via ureteroscopy, a higher success rate can be obtained with displacement into a more accessible calyx before treatment.
  
  
• Editorial Comment
  Although retrospective and non-randomized, this study suggests a great utility for the displacement techniques in the management of lower pole renal calculi. The extremely flexible nitinol basket or grasper, which limits flexion of a flexible ureteroscope minimally, can often be placed into lower pole or eccentric calyces that are inaccessible to a ureteroscope through which has been placed a laser fiber or electrohydraulic lithotripsy probe. The nitinol instruments, of which I prefer the basket, can be used to relocate the calculus into a more accessible calyx (usually an upper pole calyx). Once in this location, lithotripsy with a laser fiber or electrohydraulic lithotripsy probe can proceed much more easily and effectively. The results indicated a trend towards greater success for small calculi with the displacement compared to the in situ technique, and a significant difference in favor of displacement for stone 1 – 2 cm in diameter. With technically adequate fragmentation in most patients, the finding of a greater stone free rate in the displacement group also suggests that fragments may pass more easily from an upper pole location. Even lower pole stones that are accessible with a laser fiber or electrohydraulic lithotripsy probe, which could be treated in situ, may be more effectively treated when displaced to the upper pole. Although the mean operative time was 16 minutes longer in the displacement group, the mean stone diameter was somewhat larger in the displacement group and in a few cases displacement was performed only after technical failure of lithotripsy in situ. It was the general impression that displacement adds only a few minutes to the operative time, and that subsequent lithotripsy is performed more easily and rapidly than if the calculus had been left in situ. I recommend displacement of calculi to a more accessible calyx during ureteroscopic management of lower pole renal calculi.

Dr. J. Stuart Wolf Jr.
Associate Professor of Urology
University of Michigan
Ann Arbor, Michigan, USA